Chain assembly

ABSTRACT

The present invention discloses an improved chain assembly and a method for making the same. In general, the method of making a chain assembly in accordance with the present invention, comprises forming a plurality of links having a preselected shape and placement of apertures therein. A plurality of wire blanks are formed having an outer diameter to permit insertion into the apertures of the links. Such link is retained in a fixed position and a wire blank is inserted into each aperture of the link. On one end of each wire blank, a head is formed having a diameter larger than the aperture into which the wire blank is inserted. A mating link is placed into engagement with each link containing wire blanks with the end of each blank inserted in one aperture of the mating link in a manner to form a chain assembly. On the other end of each wire blank, a head is formed to complete interlocking of the links and blanks in forming the chain assembly.

This is a divisional of co-pending application Ser. No. 07/096,947 filedon Sept. 15, 1987 now U.S. Pat. No. 4,878,345.

FIELD OF INVENTION

The present invention relates in general, to methods of making hightolerance chain assemblies and, in particular, to methods for makingchain assemblies used in window operators which are designed to pushwindows with an assembled chain under compression and require that theassembled chain be capable of maintaining substantial structuralrigidity and rectilinearity when extended to approximate a straightline, and simultaneously provide a sufficient degree of lateral flexure.

BACKGROUND OF THE INVENTION

In general, window chain assemblies comprise links fastened to oneanother by rivets. The links are usually stamped out utilizingconventional metal stamping techniques after which several necessarysecondary operations are required to produce a finished link. Theblanks, from which the rivets are made, are usually formed by wiredrawing techniques. Examples of conventional methods for fabricatingchains of various types can be found in U.S. Pat. Nos. 1,873,619,3,125,850, 3,370,416 and 4,037,403.

However, the above-mentioned U.S. patents have not specifically orindirectly addressed the unique problems arising in the construction ofchains employed in skylight window operators.

In particular, U.S. Pat. No. 4,521,993 to Tacheny et al discloses achain operator for a window, especially designed for a skylight window.Chain operators of this general type include a chain assemblyconstructed from a plurality of solid links and a plurality of U-shapedlinks with the U-shaped links being positioned in an end-to-end abuttingrelation, and the solid links having a thickness to closely fit withinthe U-shaped links. In this general application where the chain assemblyof the window operator is designed to push the window unit undercompression rather than pull it under tension the chain links must beconstructed to provide substantial rigidity for the chain when it is ina straight configuration, so that the chain can transmit force to theswinging window unit for opening and closing thereof. The chain mustalso possess the requisite degree of lateral flexure to conform to thearcuate path traversed by swinging window unit from the window liner.

In prior art skylight chain constructions, it has thus become customaryfor the links thereof to have co-acting shapes to facilitate movement ofthe chain between straight and curved configurations, while maximizingthe strength thereof. Also, for increased strength, the rivets have beenprovided with large heads pivotally interconnecting the opposite ends ofa solid link and a pair of U-shaped links.

Therefore, in order to ensure that the finished chain assembly has (i) ahigh degree of structural rectilinearity in its extended configuration,as well as (ii) possesses the requisite degree of lateral flexure toconform to the arcuate path traversed by a swinging window unit from thewindow liner window operator chain assemblies require extremely hightolerances. However, with conventionally stamped links, there areseveral inherent limitations in the process thereof which provide linkswith specifications falling outside acceptable tolerances required bywindow operator chain assemblies. Specifically, the links produced fromconventional stamping methods have associated therewith, tapers (i.e.,edges) with die breaks up to 30°, corner tears, waves, poor surfacequality and break out, in addition to not being highly planar. Alsousing conventional stamping techniques, any additional structuralfeatures that a link must have for a particular chain assembly designmust be produced by additional operations. As with the blanks producedfrom conventional wire drawing techniques high tolerances on the orderof 0.001 inch in length are typically not achievable.

In constructing a chain assembly for use in a window operator ashereinbefore described, the requirement of high tolerance in thedimension of the parts cannot be overemphasized, since the chainassembly usually requires the assemblage of fifty or more links withrivets formed from blanks, and the resulting or total error of the finalchain assembly is the sum of all the errors in the dimensions of thecomprising components. Thus, if the tolerances of each of the individualcomponents are not maintained within a high degree of accuracy, then aresultant chain assembly cannot satisfy the following criterion: (i)that resultant chain assembly be sufficiently rigid and rectilinearalong its longitudinal dimension when in its extended configuration, and(ii) that it possess sufficient lateral flexure as to conform to thearcuate traverse of the swinging window unit from the liner to which theswinging window unit is mounted.

While the prior art has addressed the problem associated withinadequately configured chain assemblies with respect to criterion (i)and (ii) discussed hereabove, the solutions thereto have been whollyinadequate for purposes of obtaining the objects of the presentinvention. Therefore, conventional chain construction techniques havebeen retained and post assembly corrective measures have been developedto compensate for the inherent shortcomings of conventional chainconstruction methods. Such conventional chain construction techniquesinvolve the intentional introduction of "error" in each link such thatthe assembled chain assembly possesses a predetermined degree of arcuatecurvature, after which corrective measures are taken. The principaltechnique used to correct the shape of an assembled chain for a windowoperator has been to use jaw-like apparatus to "overbend" completelyassembled chains having predetermined arcuate curvature to therebycorrect its shape as to satisfy criterion (i) and (ii) hereabove, butthis operation results of course, in loosening or tightening thecomponent parts and preventing the establishment of preciseinterrelationships therebetween. Moreover, since resultant chainassemblies will not require the same degree of overbending to correcttheir shapes, this method more often than not produces chain assemblieswhich fail to meet criterion (i) and (ii) as desired. One importantconsequence of this overtightening and loosening of rivets is that thisrenders the chain assembly extremely stiff at locations along the chainlength which prevents the same from turning about the drive sprocket ofa chain operator. Often, this resistance of the chain to turn about thedrive sprocket, causes the chain operator to fail.

As important however, chains made from stainless steel and other metalsdesired for their non-corrosive properties, cannot be subjected to suchoverbending procedures to correct the shape of a chain assembly producedfrom components of low tolerance, as stainless steel and like metalswill shear and fracture when subjected to forces associated withoverbending procedures. This fact has thus prevented the fabrication ofskylight chains from highly desired materials such as stainless steel,and other metals desired for their non-corrosive properties. As a resultof this fact, prior art chain assemblies for chain operators haveresorted to the use of "mild" steel to fabricate the link plates ofchain assemblies. In order to provide a non-corrosive outer coating tothe mild steel links, barrel plating processes are typically employed.However, even with the finest plating processes and equipment, unevenplating of link plates occurs, the result of which is premature wearingaway of deposited non-corrosive coatings. This renders link plates soexposed susceptible to oxidation and corrosion thereby reducing thequality of appearance and performance of such chain assemblies, andoperators employing the same.

Therefore, there is a great need in the art for chain assemblies made ofnon-corrosive materials, which do not require plating, and which, suchas stainless steel, can be used with chain operators for windows.

In view of the above-recognized problems and the prior art solutionsthereto, it therefore becomes a primary object of the present inventionto provide a method for making chain assemblies for window and likeoperators, which possess structural features of substantialrectilinearity along its longitudinal dimension when in its extendedconfiguration, and sufficient lateral flexure for conforming to thearcuate traverse of a swinging window unit from its liner.

It is also an object of the present invention to provide a method formaking a chain assembly for a window operator, wherein the links andrivets thereof are made of stainless steel, thereby eliminating therequirement of plating link plates with non-corrosive coatings.

It is a further object of the present invention to provide such a methodwherein the chain assembly is precision-formed from links and rivetshaving ultra-high tolerances, as to produce chain assemblies therefromhaving the desired degree of longitudinal rectilinearity when extended,and the required lateral flexure to conform to arcuate geometry, withoututilizing "overbending" and similar shape-corrective measures.

It is a further object of the present invention to provide such a methodutilizing fine blanking metal working principles to form the links ofthe chain assembly, and a combined "orbital" riveting method and"spinning method" for forming the heads of the rivets which hold thelinks together.

It is a further object of the present invention to provide such methodfor making a chain assembly which uses only one type of link to be usedin forming the chain assembly.

It is an even further object of the present invention to provide such amethod which is capable of mass producing high tolerance chainassemblies at a low cost.

It is an even further object of the present invention to provide suchmethod which is readily adaptable to automated mass production of chainassemblies in accordance with the principles of the present invention.

It is a further object of the present invention to provide a chainassembly produced by such method.

It is an even further object of the present invention to provide amethod for making chain assemblies for window operators, whicheliminates the requirement of secondary operations such as "overbending"procedures performed on chain assemblies.

SUMMARY OF THE INVENTION

In general, the method of making a chain assembly in accordance with thepresent invention, comprises forming a plurality of links having apreselected shape and placement of apertures therein. A plurality ofwire blanks are formed having an outer diameter to permit insertion intothe apertures of the links. Each link is retained in a fixed positionand a wire blank is inserted into each aperture of the link. On one endof each wire blank, a head is formed having a diameter larger than theaperture into which the wire blank is inserted. A mating link is placedinto engagement with each link containing wire blanks with the end ofeach blank inserted in one aperture of the mating link in a manner toform a chain assembly. On the other end of each wire blank, a head isformed to complete interlocking of the links and blanks in forming thechain assembly.

In forming the plurality of links, a fine blanking process can be usedin which bends are introduced into the shape of each link. The pluralityof wire blanks can be formed by drawing wire and shearing the wire intoa plurality of predetermined lengths. The blanks can be retained in afixed position by inserting the same into respective holes of a holdingfixture, as to allow one end of the blank to protrude therefrom at apredetermined height above the surface of the holding fixture. The linkscan then be positioned onto the blanks protruding from the holdingfixture, and the holding fixture precisely positioned with respect to ameans for forming a head onto the protruding blank. Using an orbitalriveting method, the head can be formed onto each protruding blank as toproduce a rivet from each blank.

One advantage derived from the orbital riveting process is that therivet blank does not rotate within the link plate and therefore does notneed to be held against rotation during the head forming process.Another advantage is that while the head is being formed, the pressureapplied also forces the plastically deformed, i.e., swelled, metal ofthe blanks to expand into tight frictional engagement with the walls ofthe circular apertures formed in the link plates. This tight frictionalengagement allows a subsequent "spinning" process to be used to form thehead on the opposite end of the blank without needing to hold the rivetblank from turning.

In forming heads on the other end of each wire blank, the links andblanks can be positioned into a guide fixture as to dispose the headlessends of the wire blanks, accessible to a means for forming a head. Usinga conventional spinning method, heads are then formed on the ends of thewire blanks to thereby complete interlocking of the links and blanks toform the chain assembly of the present invention.

Thus, an even further result of the present invention is to provide amethod of making a chain for a window operator, which is simple andemploys, in part, readily available technology.

The present invention accordingly comprises the method and chainassembly, together with their steps, parts, components, andinterrelationships, which are exemplified in the present disclosure, thescope of which will be indicated by the appended claims.

Other and further objects will be explained hereinafter and will be moreparticularly delineated in the appended claims, and the other objects ofthe present invention will, in part, be obvious to one with ordinaryskill in the art to which the present invention pertains, and will, inpart, appear obvious hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the objects of the present invention,reference is made to the following detailed description of the preferredembodiment, which is to be taken in connection with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of a skylight window supported in its openposition by a chain window operator, employing the chain of the presentinvention;

FIG. 2 is a perspective view of a fragment of section of the chainassembly of the preferred embodiment showing two link plates withadjacent links connected together by rivets;

FIG. 3 is a side view of a chain assembly for a window operatorfabricated in accordance with the method hereof;

FIG. 4 is a plan view of an extended chain assembly along itslongitudinal axis, illustrating the preferred degree of lateral flexure(i.e., arcuateness) required of the chain assembly hereof;

FIG. 5 is a side view of a link of a chain assembly for a windowoperator;

FIG. 6 is a side view of a rivet blank for use in forming the chainassembly of the present invention;

FIG. 7 is a perspective view of a link and rivet subassembly formedduring an intermediate step of the method of the present invention;

FIG. 8A is a perspective view of the holding fixture used in themanufacture of the chain assembly of the present invention;

FIG. 8B is a sectional side view of the holding fixture of FIG. 8A;

FIG. 8C is a perspective view of the holding fixture showing rivetblanks inserted therein;

FIG. 8D is a perspective view of the holding fixture showing linkspositioned onto the blanks protruding from the upper plate;

FIG. 8E is a sectional side view of a fragmentary portion of a linkplate through which a rivet passes with a head formed thereon;

FIG. 8F is a perspective view of the guide fixture showing a chainassembly positioned therein as to dispose the ends of the rivets withoutheads formed thereon accessible to apparatus for forming a head; and

FIG. 8G is a perspective view of a fragmentary portion of the completechain assembly.

DETAILED DESCRIPTION

It is now in order to describe in a best mode embodiment, the details ofthe method and apparatus for making a chain assembly for a windowoperator.

Referring to FIGS. 1, 2, 3 and 4, in particular, a chain assembly madein accordance with the method of the present invention is shown. In FIG.1, a chain assembly 1 of a window operator 22 is shown supporting in itsopen position, a swinging window unit 2 of a skylight window assembly 3.The drawing of FIG. 1 serves to illustrate that the chain assembly 1 hassubstantial rectilinearity along its longitudinal dimension when in itsextended configuration, and also sufficient lateral flexure forconforming to the arcuate traverse of a swinging window unit 2 from itsliner 4.

In FIG. 2, a section of the chain assembly hereof is shown, wherein twolink plates of identical geometry are placed back to back with rivetspassing through holes formed therein. The drawing illustrates how asingle link plate can be used in constructing the chain assembly.

In FIG. 3, a chain assembly 1 constructed pursuant to the method hereof,is shown extended along a planar surface, which illustrates that a chainassembly so constructed will possess the required degree of rigidity andlongitudinal rectilinearity, formed without the requirement of"overbending" operations discussed hereinbefore. The parameter d₁signifies the degree to which the chain assembly deviates fromlongitudinal rectilinearity.

In FIG. 4, the chain assembly 1 of FIGS. 1, 2 and 3 is shownlongitudinally extended and disposed on its link plates along a planarsurface, which illustrates that a chain assembly constructed inaccordance with the method hereof will possess the required degree oflateral flexure formed without the requirement of subsequent"overbending" operations. As discussed hereinbefore, a sufficient degreeof lateral flexure and substantial rigidity and rectilinearity of achain is required in skylight chain operator applications, and whenusing desired metals such as stainless steel, overbending operationscannot be used as corrective measures. As illustrated in FIG. 4, thetolerance parameter d₂ provides a measure of the lateral flexure of thechain assembly. It has been empirically discovered that in the case ofskylight chain operator applications, the tolerance parameter d₂ in anunloaded condition preferably should be within the range of 5/16 toabout 3/8 of an inch for a chain assembly length of about 13.5 inchescomprising about 27 link lengths in the preferred embodiment hereof.

Referring to FIGS. 5 and 6, a link (plate) 5 and (rivet) blank 6 areshown, respectively. The link 5 comprises a plate 7 having a flange 8bent therein, which in cooperation with other flanges of adjacent links,allows the chain assembly 1 to extend in a substantially rectilinearconfiguration. In the link 5, a hole (i.e., circular aperture) is formedunder each edge 9 of the flange 8. In view of the high tolerances neededfor the individual components of the chain assembly having theaforementioned structural properties, a "fine blanking" process can beused to form the geometry of the link (plates) 5, and the holes andbends in flange 8 introduced therein to ensure that such components arefabricated having the aforementioned tolerances.

The distance B is hereinafter designated as the length measure from oneedge 9 of the flange 8 to the other. The distance A is hereinafterdesignated as the distance between the holes, measured from center tocenter. It has been discovered that "B" cannot be larger than "A" by0.0005 inches if a resulting chain assembly is to be formed having anacceptable measure of longitudinal rectilinearity. Using the fineblanking process step of the method hereof, such tolerances can beachieved

As for the diameter D of the (rivet) blanks 6, it has been discoveredthat diameter tolerances is preferably maintained within ±0.00025 of aninch, if the sufficient lateral flexure of the chain assembly is to beobtained. However, hitherto, the standard tolerance for stainless steelcold headed rivets has been ±0.005 of an inch.

Using the "fine blanking" process step of the method of the presentinvention, diameter tolerances of holes in link plates are preferablymaintained within at least ±0.00025 of an inch, and higher tolerancescan be obtained using the fine blanking process.

State-of-the-art fine blanking equipment available from AmericanFeintool, Inc. of Cincinnati, Ohio, has been found to be satisfactoryfor fabricating the link plates 5 within the required design tolerancesof the preferred embodiment. One advantage of using the fine blankingprocess is that each link plate is completely fabricated in a singleoperation, eliminating the inaccuracy stemming from moving the linkplate 5 through progressive tooling operations where tolerancestypically change. Another advantage is that with the fine blankingprocess, the link plates so produced are flat, thereby eliminating theproblem of unflat parts produced with conventional stamping and punchingoperations. Other advantages of fine blanking are the elimination ofsecondary operations, such as, for example, the need to drill holes,grinding for finish and thickness, countersinking, and milling the legs.

Regarding the length C of the blanks, it has also been discovered thatthe tolerance is preferably maintained to about ±0.001 of an inch. Thefabrication of blanks 6 within the aforementioned tolerance limits, canbe produced by precisely drawing wire using conventional techniques, andprecisely shearing the wire into a plurality of predetermined lengths.

Referring to FIGS. 8A, 8B, 8C, 8D, 8E, 8F and 8G, the various steps ofthe method hereof are illustrated.

In FIG. 8A, a holding fixture 10 is shown, comprising an upper plate 11and a lower plate 12, where the upper plate 11 has a plurality of holes13A formed therein, where the distance between each pair of holes isequal to B as designated in FIG. 5. Into each of these holes, a blank 6precisely fits from which a rivet is to be made. Notably the depth ofeach hole must be a predetermined depth as to allow the ends of theblanks to protrude therefrom at a predetermined height above the surfaceof the holding fixture. Typically this predetermined height is in therange of about 0.035 of an inch. The diameter of each hole formed in theupper plate 13A is such that blanks 6 are precisely received therein,can be easily removed therefrom with minimal force and heads of desireddimensions are formed. Also formed in the top surface of the upper plate11, is a longitudinally extending groove 14 running parallel with theline of holes 13A. This groove is for accommodating the downwardlyextending flange 8 of link plate 5, the remainder of which is maintainedin flat surface-to-surface registration with the holding fixture 10during the rivet head forming process.

As illustrated in FIG. 8C, the lower plate 12 has a plurality of holesformed 13B therein which in the preferred embodiment, coincides with theplurality of holes 13A formed in the upper plate 11. Plurality of holes13B are used to align the holding fixture 10 with respect to apparatusfor forming a head on a (rivet) blank 6, as further described in a latersection of the description.

After producing a plurality of links 5 using a fine blanking process,the blanks 6 are inserted into the respective holes 13A of the holdingfixture 10 as to allow one end thereof to protrude from the holdingfixture 10 at a predetermined height thereabove as indicated in FIG. 8C.In connection therewith, there are a variety of ways in which the blanks6 can be inserted into the holding fixture 10. In the preferredembodiment, a circular-wave vibration delivery system (not shown), wellknown in the art can be used.

As illustrated in FIG. 8D, the link plates 5 are positioned onto theblanks 6 protruding from the holding fixture 10.

As illustrated in FIG. 8D apparatus 18 for forming a rivet head onto theprotruding blank 6, is positioned with respect to the holding fixture10, lubrication is applied thereto, and then a head is formed onto eachprotruding blank 6 using an "orbital riveting" method, as to produce arivet from each blank 6. In this connection, reference is made to U.S.Pat. No. 1,873,619 to Mojonnier which discloses an orbital spinningmethod and to U.S. Pat. No. 3,125,850 to Onulak et al. which disclose aspinning method having principal advantages of the same.

Using such head forming techniques, considerable pressure can be appliedto the ends of the blank 6, while the orbital spinning tool spins.Through this action heads are spun or formed upon the ends of the blanks6 and a fully headed rivet is produced. Also, at the same time that theheads are being formed, the pressure applied also forces the plasticallydeformed metal of the blanks to expand into tight frictional engagementwith the walls of the circular apertures formed in the link plates asillustrated in FIG. 8E, and thereby establishes what is practically anintegral connection with the link plate 5. In essence, this processprevents rotation of the blank with respect to the link to which it isjoined a desirable feature when forming heads using the orbital spinningmethod. At the end of this step of the method hereof, a link and rivetsubassembly 15 is formed as illustrated in FIG. 7.

After removing the links and rivet subassemblies 15, from the holdingfixture 10, the links and rivet subassemblies 15 and mating link plates5 are assembled to form a chain assembly 16. This step is achieved byplacing a mating link 5 into engagement with each link 5 containing awire blank 6 (i.e., link and rivet subassembly) with the end of eachblank 6 inserted in one aperture in the mating link 5 in a manner toform the chain assembly 16. Notably the chain assembly 16 can beachieved by manual operations, or by automated procedures.

Referring to FIG. 8F, the chain assembly 16 is shown positioned onto aguide fixture 17, as to dispose the ends of the rivets without headsformed thereon accessible to apparatus for forming a head 18. The guidefixture 17 in the preferred embodiment, includes a bottom plate 20 andtwo parallely spaced-apart walls 19A and 19B mounted thereon forming aguide channel 21 with the distance between the walls 19A and 19Bsubstantially equal to the height of the link and rivet subassembly 15.The chain assembly 16 can be positioned into the guide channel 21 withthe "orbitally spun" heads disposed against the bottom plate 20 of thechannel 21, and the unheaded ends of the (rivet) blanks 6 facing towardapparatus for forming heads 18.

Using a conventional spinning method, heads can be spun onto theunheaded ends of the blanks 6 while the chain assembly 16 is sopositioned in the guide fixture 17. Notably, since each rivet blank 6 issecured to its respective link plate 5, the rivet blank 6 is not free tospin, and therefore will allow a head to be formed thereon using aconventional spinning method. Forming rivet heads using the spinningmethod does not require great pressure and intrinsically providessufficient clearance between the underside of heads and adjacent surfaceof link plates. This clearance between each head and link plate, whenadditively combined in an assembled chain assembly, provides the desireddegree of lateral flexure of the chain assembly.

Once positioned in the guide fixture 17, light lubrication is applied tothe ends of the rivet blanks 6 without heads, and a head is spun (i.e.,formed) thereon using a conventional spinning method. After this step inthe method hereof, a completed chain assembly 19 is formed asillustrated, in part, in FIG. 8G.

In accordance with the principles of the present invention, themanufacture of the chain assembly involves forming links with bends andapertures, and wire blanks having a diameter matched to the apertures.The blanks 6 are inserted into the links 5, and using an orbitalspinning method, for example, heads are formed onto the ends of theblanks 6 to form rivets. Mating links 5 are then placed into engagementwith each link containing wire blanks, where the end of each blank 6 isinserted in one aperture in the mating link 5, in a manner to form achain assembly 16. Using a conventional spinning method, heads areformed on the other end of each blank 6 to complete interlocking of thelinks 5 and blanks 6 in forming the chain assembly 16.

It will be noted that the method of the present invention is amendableto automation, and therefore can be implemented using a rotary tablewith several stations, or using an assembly line format as with mostautomatable procedures.

Further modification of the present invention herein disclosed, willoccur to persons skilled in the art to which the present inventionpertains, and all such modifications are deemed to be within the scopeand spirit of the present invention defined by the appended claims.

What is claimed is:
 1. A chain for opening a window or the like,comprising:a plurality of interconnected links, each of said linksincluding a plate portion and a flange portion extending at an anglewith respect to said plate portion, each of said links being formed froma non-corrosive material which is not amenable to overbending; a pair ofopenings extending through said plate portions of each of said links,said openings each having a diameter, the diameter of said openingsbeing formed with tolerances not exceeding 0.00025 inch; a plurality ofrivets extending, respectively, through each of said openings andconnecting said links, each of said rivets including first and secondheads connected by a substantially straight, cylindrical shank, saidrivets being formed from cylindrical blanks, the diameters of saidblanks being within tolerances of 0.00025 inch; said links beingconstructed and interconnected so as to provide longitudinal rigidity sothat said interconnected so links can be used to push a window or thelike, to provide lateral flexibility to conform to an arcuate pathtraversed by a swinging window or the like, and to provide longitudinalflexibility to allow each of said interconnected links to freely rotateabout said respective rivets between a first position providing saidlongitudinal rigidity and a second position wherein said interconnectedlinks assume a curved configuration.
 2. Chain as described in claim 1wherein said links are arranged first and second interconnected pairs oflinks, said first pairs of said links being arranged, respectively, inalternating and overlapping sequence with said second pairs of links,said first pairs of links being arranged such that said flange portionsof each pair of links extend toward each other, said second pair oflinks being arranged such that said flange portions of each pair oflinks extend away from each other and said plate portions of each secondpair of links adjoin each other, said adjoining plate portions of eachof said second pairs of links extending, respectively, between saidplate portions of the respective first pairs of links respectivelyconnected to said second pairs of links.
 3. A chain as described inclaim 1 wherein each of said rivets is in tight frictional engagementwith one of said links, there being a clearance between said rivet andanother of the links through which said rivet passes, said clearanceproviding lateral flexibility of the interconnected links.
 4. A chain asdescribed in claim 1 wherein said material is stainless steel.
 5. Achain as described in claim 1 wherein none of said rivets includes ahollow formed therein, each of said rivets being of solid construction.